This invention relates to the field of periscopes, and more particularly, to a high accuracy periscope assembly and a method of constructing a high accuracy periscope assembly.
Periscopes are old in the art and normally consist of some sort of cylindrical or tubular central chamber into which are placed two spaced apart reflecting surfaces. The reflecting surfaces face each other so that a person looking into an opening at one end of the cylindrical member will see the image which is reflected off of the more remotely situated reflecting surface; since this image will be visible through a second opening in the cylindrical member near the second reflecting surface.
Periscopes can also be used to reflect light beams having a certain direction upon entering the periscope, so that the light beams exit the periscope having substantially the same direction, or some other desired direction, but displaced linearly a distance equivalent to the separation distance of the reflecting surfaces. Depending upon the accuracy needed for the periscope, the alignment of the reflecting surfaces can be varied.
Accordingly, the accuracy of a periscope assembly is determined by the alignment between a light beam entering the periscope and the same light beam exiting the periscope. The more accurately aligned the entering and exiting light beams are, the higher the accuracy of the periscope.
Methods which have been previously used to achieve high accuracy, or guidance, of light beams are seen in the following United States patents.
U.S. Pat. No. 5,024,514 to Bleier et al. is directed to a Lateral Transfer Retroreflector and a Roof Mirror for Same. As seen in the figures, the retroreflector of the '514 patent has a mirror panel 110 and a roof mirror 10 which are offset a distance corresponding to the length of tubular member 130. A retroreflector is a device for redirecting a light beam along a path which is offset from the entering light beam and which is in a direction opposite to the incoming light beam.
Specifically, the '514 patent is directed to a lateral transfer retroreflector, wherein mirror panel 110 and roof mirror 10 are adhered to tubular member 130 through the use of three mounting pads located on each of mirror panel 110 and roof mirror 10. However, the structure of the '514 patent does not allow (1) the direction of the exiting light beam to be substantially the same as that for the entering light beam and (2) for exacting alignment of the reflective surfaces of mirror panel 110 and roof mirror 10, as is presented in the present invention
U.S. Pat. No. 4,975,573 to Girard for an Optical Test Bench shows another previously used method of aligning light beams. As shown in FIGS. 5-18, and specifically, FIGS. 9 and 12, a laser alignment periscope system 192 (FIG. 9) permits exact adjustment of the relative inclination of parabolic mirrors 112 and 114 via adjusting bolts and nuts 182-188 (FIG. 12). The method of achieving the adjustment of the relative inclination of mirrors 112 and 114 is most clearly illustrated in FIGS. 15-18. The distinctive quality of the '573 patent with respect to the present invention, is that the '573 patent does not achieve its high accuracy through adjustment of periscope system 192, but through adjustment of bolts 182-188 which secure mirrors 112 and 114 to mounting plate 116. Accordingly, it is not periscope 192 of the '573 patent which achieves the high precision.
U.S. Pat. No. 4,933,127 to McRight for a Multi-Faceted Optical Device for a Laser Scanner, shows, in FIG. 3, mirrors 110 adhere to three raised pads 112 located on mirror receiving faces 108. Pads 112 define three planes of contact upon which mirrors 110 are adhered to receiving faces 108. However, no method of achieving final exacting alignment of the mirrors is shown, and therefore, the invention of the '127 patent is distinguishable from the present invention.
Finally, U.S. Pat. No. 4,277,141 for a Multi-Faceted Mirror and Assembly Fixture and Method of Making such Mirror shows another method which is old in the art for achieving the accurate alignment of reflecting surfaces As seen in FIG. 1, mirrors 15 are bonded to support or core element 11 by epoxy 14. To attach mirrors 15 to support 11, mirrors 15 are held in accurate positions that are independent of faces 16 of support 11 and epoxy 14 is injected between faces 16 and mirrors 15 to form a secure bond. There is, however, no method of adjusting the accuracy of mirrors 15 after epoxy 14 is cured.
Accordingly, it would be desirable to provide a high accuracy periscope assembly in which the direction of an exiting light beam is substantially the same as the direction for an entering light beam and which achieves its accuracy through a kinematic mounting system consisting of mounting pads to adhere the reflecting surfaces to the tubular member and a fourth alignment pad for finally aligning the reflecting surfaces and securing the reflecting surfaces to the tubular member in their aligned positions.